Estimate your monthly payments and total interest costs.
Estimated Monthly Payment
Total Principal
Total Interest
Total Lifetime Cost
Understanding Your Mortgage Payments
Purchasing a home is one of the most significant financial decisions you'll ever make. Our Mortgage Repayment Calculator helps you break down your monthly obligations so you can budget effectively and understand the long-term cost of borrowing.
How is the Mortgage Calculated?
The calculation uses the standard amortization formula to determine the fixed monthly payment required to pay off the loan and interest by the end of the term:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
M: Total monthly payment
P: Principal loan amount
i: Monthly interest rate (Annual Rate / 12)
n: Number of months in the loan term
Key Components of Your Payment
While our calculator focuses on Principal and Interest (P&I), remember that your actual "all-in" monthly payment often includes other costs:
Property Taxes: Annual taxes levied by your local government.
Homeowners Insurance: Protection against damage and liability.
PMI (Private Mortgage Insurance): Required if your down payment is less than 20%.
HOA Fees: Fees paid to a Homeowners Association if applicable.
Mortgage Calculation Example
Suppose you purchase a home with a loan amount of $300,000 at a 6.5% interest rate for a 30-year term:
Monthly Payment: Approximately $1,896.20
Total Interest Paid: $382,633.40
Total Cost of Loan: $682,633.40
As you can see, over 30 years, the interest paid can actually exceed the original loan amount. This is why shopping for a competitive interest rate is vital for long-term savings.
function calculateMortgage() {
var principal = parseFloat(document.getElementById('loanAmount').value);
var annualRate = parseFloat(document.getElementById('interestRate').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var resultDiv = document.getElementById('mortgageResult');
if (isNaN(principal) || isNaN(annualRate) || isNaN(years) || principal <= 0 || annualRate <= 0 || years <= 0) {
alert('Please enter valid positive numbers for all fields.');
resultDiv.style.display = 'none';
return;
}
var monthlyRate = (annualRate / 100) / 12;
var numberOfPayments = years * 12;
// Monthly Payment Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var x = Math.pow(1 + monthlyRate, numberOfPayments);
var monthly = (principal * x * monthlyRate) / (x – 1);
if (!isFinite(monthly) || monthly <= 0) {
alert('There was an error in calculation. Please check your inputs.');
return;
}
var totalPayment = monthly * numberOfPayments;
var totalInterest = totalPayment – principal;
document.getElementById('monthlyOutput').innerHTML = '$' + monthly.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalPrincipalOutput').innerHTML = '$' + principal.toLocaleString();
document.getElementById('totalInterestOutput').innerHTML = '$' + totalInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalCostOutput').innerHTML = '$' + totalPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
resultDiv.style.display = 'block';
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}